Interpretive Summary: Beet mild yellowing virus (BMYV) is another member of the virus yellows complex, causing beet leaves to yellow prematurely. BMYV is a member of the genus Polerovirus, in the family Luteoviridae, and is serologically related to Beet chlorosis virus (BChV) and Beet western yellows virus (BWYV). BMYV is common in Europe, but has not been identified in the United States. Sugar yield and quality can be reduced as a result of infection. Symptoms of BMYV infection include interveinal and uniform yellowing of leaf tissue (Plate 22), thickening and brittleness of older leaves. BMYV symptoms resemble those of Beet yellows virus and Beet western yellows virus (BWYV), and to a lesser extent, Beet chlorosis virus (BChV). BMYV particles are small, isometric virions, about 26 nm in diameter. BMYV has a genetic organization and expression typical of other poleroviruses including 6 open reading frames (ORFs). The green peach aphid (Myzus persicae) is the primary vector of BMYV, however other aphid species can also transmit the virus. BMYV becomes circulative but does not multiply in the vector. The virus is retained during molting, but is not transmitted to the progeny of the vector. BMYV is not mechanically transmissible, and is not transmitted by seed or pollen.